Biological Constraints Outweigh Neutral Processes in Shaping the Hummingbird-Plant Network of a Tropical Dry Forest

Plant–animal interactions have shaped much of Earth’s biodiversity. Their structure probably results from a combination of neutrality and constraints imposed by species’ traits, such as phenotypes, phenologies, and spatial distributions, which may affect their stability and coevolutionary processes. Understanding how biological communities are structured remains a major challenge in ecology. To explore this, a hummingbird–plant interaction network from a tropical dry forest in Mexico was surveyed monthly over two years to identify the main drivers of species interactions and network structure. By combining data on morphology, phenology, and the abundance of flowers and hummingbirds, we examined whether biological constraints or neutral processes better explain interaction frequencies and how these factors influence network metrics. Our results indicate that a biological constraint—species phenology—is the most important predictor of plant–hummingbird interaction frequencies. Conversely, null models incorporating abundance best projected most network parameters, suggesting that a neutral process is crucial for predicting these metrics. Interaction networks serve as valuable tools for studying ecological processes. Because previous studies have reported contrasting results regarding the drivers of hummingbird–plant interactions, further comparative studies across ecosystems are still needed to evaluate the generality of these mechanisms.